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DISTRIBUTION OF LAND AND WATER ON THE PLANET

RATIO OF LAND AND SEA AREAS


 

I. Continental hemisphere   II. Oceanic hemisphere
Maximum depths of oceans in meters





The area of the Earth surface is equal to 510,100,000 km2. Land covers 148,800,000 km2 (29.2%) and the World Ocean covers 361,300,000 km2 (70.8%). The World Ocean is a continuous water “blanket” over the Earth adjacent to all of the continents and islands and possesses a generally salty structure.

In the Northern Hemisphere, the World Ocean occupies 61% of the area and in the Southern Hemisphere, 81%. If we were able to arbitrarily divide the Globe into two equal parts so that in one hemisphere the land predominated, and in the other the water, water will appear to cover more than half of the area (53%). The oceanic hemisphere takes up about takes 91% of the area. The land and sea are also non-uniformly distributed on the planet. Land predominates only between latitudes of 45° N and 70° N, and to the south, from latitude 70° S to the South Pole. Water predominates over the remaining part of Globe. The shapes of the shorelines, bottom relief, systems of oceanic currents, tides, atmospheric circulation and a number of other criteria subdivide the World Ocean into the Pacific, Atlantic, Indian and Arctic Oceans.

With the broadening of knowledge about Antarctic waters as a unified, physical-geographical area, some scientists now separate the waters surrounding the Antarctic continent, an area of 86 million km2, into a different water body: the Southern Ocean. Although widely used in scientific and other literature, the term “Southern Ocean” has not yet received official status.
 
 

THE AREAS AND DEPTHS OF OCEANS

Ocean and seas
Area in million km2
% of the area of the World Ocean
Depth, m
mean 
Depth, m 
greatest
Locations of the greatest depths of the Ocean
Pacific
178.8
49.5
3 976
11 022
Marianas Trench
Atlantic
91.7
25.4
3 597
8 742
Puerto Rico Trench
Indian
76.2
21.0
3 711
7 729
Sunda Trench
Arctic
14.7
4.1
1 225
5 608
Greenland Sea (Molloy Deep)
World Ocean
361.3
100.0
3 711
11 022
Marianas Trench

On the surface of the Earth, altitudes less than 1,000 m and depths from 3,000 up to 6,000 m predominate. It is shown on a hypsographic profile constructed from the areas derived from various kinds of charts, showing the heights of the land and the depths of the Ocean over the entire planet.
 
 

Distribution of land and water by latitude (%)
 
 

Hypsographic profile

 1. Sea level
2. Continental shelf
3. Continental slope
4. The Ocean floor 
5. Mean depth of the World Ocean 3711m 
6. Mean altitude of the land 840m
7. Jomolungma 8848m
8. Marianas Trench11022m
VOLUME OF THE WATERS OF THE WORLD OCEAN
The water cover of the Earth (called the “Hydrosphere”) has volume of 1,389,500,000 million km2, and 97.4% consists of salt water. Of this volume, 96.5% is in the World Ocean, and 0.9% is in salty underground and lake waters.

Fresh water comprises only 2.6% of the total volume of the Hydrosphere. This is the water contained in the atmosphere, rivers, lakes, glaciers, underground and ground water, and also the waters contained internally in animals and plants.

The waters of the World Ocean are distinguished from fresh water by their differing physical and chemical properties. By well-defined differences and a complex exchange of energy and matter peculiar to the animal and plant kingdoms, a subclass of the Hydrosphere exists, called the “Oceanosphere”, can be separated from the rest of the hydrosphere. The Oceanosphere has a great influence on the formation and changes of the natural world.

The World Ocean (Oceanosphere) contains on the order of 1,340.7 million km3 of water, making up 1/800th of the total volume of the Earth (1,083.3 billion km3). Alternatively, the volume of fresh water is about 35.8 million km3. If the Oceanosphere was shown in the form of a sphere, its radius would be equal to 690 km, or 0.11 mean radii of the Earth (6,371 km).

In the process of exchanging water with the atmosphere and continents, World Ocean annually produces atmospheric precipitation of about 458,000 km3; both rivers and ground water produce about 48,000 km3 of water. Evaporation from the surface of the Ocean produces 506,000 km3. In comparison with the total volume of oceanosphere, these figures of exchange are insignificant. There is a much greater exchange between waters of the different oceans, that is, about 18,370 km3 of water is annually exchanged between the oceans. This process redistributes the oceanic reserves of heat and salt, and has a great influence on both atmospheric processes and the characteristics of the whole Oceanosphere.
 
 

Volume ratios of waters of the land and in the World Ocean

1. The World Ocean

2. Glaciers and permanent snow cover

3. Ground water, permafrost

4. Lakes, rivers, bogs

5. Water in atmosphere

Sea water distribution volume at different depths (millions of km3)








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